Shape memory alloy actuators for aircraft landing gear

ABSTRACT

Shape memory alloy actuators for aircraft landing gear are provided. In one embodiment a retractable aircraft landing gear system is provided. This embodiment includes a shape memory spring strut having a first end and a second end wherein the shape memory spring strut is extendable from a first length to a second length and the shape memory spring strut contains a shape memory alloy. This embodiment also includes a shape memory spring strut activation line connected to the shape memory spring strut wherein the shape memory spring strut activation line may be configured to activate the shape memory spring strut and a longitudinal connecting member having a first segment and a second segment wherein the first segment is in pivotal contact with the first end of the shape memory spring strut and the second segment supports a wheel rotatably mounted on a pin. The connecting member may be moveable along a line of travel from an extended position to a retracted position in this embodiment.

RELATED APPLICATIONS

[0001] This is a Continuation-In-Part of Application Ser. No. 09/467,749filed Dec. 20, 1999 and entitled “Heat Converter Engine Using A ShapeMemory Alloy Actuator.”

FIELD OF THE INVENTION

[0002] The present invention relates to mechanical actuators. Moreparticularly, the present invention regards using a shape memory alloyas a power source in mechanical actuators for controlling aircraftlanding gear.

BACKGROUND INFORMATION

[0003] A class of materials called shape memory alloys (SMA) exhibits anon-linear relationship between stress and strain when exposed totemperature changes. These alloys undergo a temperature related phasechange that allows the SMA to return to any mechanical configurationimposed on the SMA when it is annealed. When the SMA is below itscritical temperature, it becomes malleable and may be deformed into anyarbitrary shape. Upon heating the SMA above the critical temperature, itundergoes a change in crystal structure and quickly resumes its stifforiginal shape. Cooling the SMA to below the critical temperature will,again, cause it to return it to the cold malleable condition allowing itto be deformed, but always returning to its original shape when it isheated above the critical temperature. The best known SMA is Nitinol, atitanium nickel alloy, having 53.5-56.5% nickel content by weight. Witha temperature change of as little as 18° F., Nitinol can exert a forceof as much as 60,000 psi when exerted against a resistance to changingits shape.

[0004] Several prior art patents have disclosed the use of SMAs asactuators. For example, U.S. Pat. No. 4,932,210 to Julien et al.discloses the use of a shape memory alloy actuator for accuratelypointing or aligning a moveable object. The SMA elements are arranged ina push-pull configuration so that one element in the activated statemoves the object while another element on the opposite side in the softstate acts as a dynamic damper to prevent overtravel of the object.Similarly, U.S. Pat. No. 5,061,914 to Busch et al. discloses SMAactuators that are mechanically coupled to one or more movable elementssuch that the temperature induced deformation of the actuators exerts aforce or generates motion of the mechanical element. However, thesesystems are used for precision type operations and produce little outputpower. These systems are not suitable for producing enough power todrive small pumps or motors, for example, a water pump in an automobile.

[0005] Several prior art patents also describe the use of SMAs to drivea shaft in a motor. For example, U.S. Pat. No, 4,665,334 to Jamiesondiscloses a rotary stepping device having a rotatable shaft which isdriven by a coiled spring clutch. An actuator made of an SMA is heatedand used to pull the spring clutch to tighten it and rotate the shaft.When the SMA is cooled it returns to its malleable state and releasesthe spring clutch which loosens from around the shaft and returns to itsoriginal position without rotating the shaft in the opposite direction.U.S. Pat. No. 4,027,479 to Cory discloses a heat engine with an endlessbelt which includes a number of high density elements secured to lengthsof SMA wire. The belt is attached to a pulley connected to a shaft. Twoportions of the belt are maintained at different temperatures and thebelt is constrained to move the elements in a continuous path into afield attracting the elements at the hot portion and out of the field atthe cold portion. The SMA wire in the cold portion is stretched and theSMA wire in the hot portion contracts resulting in higher elementdensity on the portion entering the field and thus a net force drivesthe belt about the pulley. However, these systems are also limited intheir energy output and their complicated construction makes themimpractical for use in standard machinery such as an engine or motor.

SUMMARY OF THE INVENTION

[0006] Shape memory alloy actuators for aircraft landing gear areprovided. In one embodiment a retractable aircraft landing gear systemis provided. This embodiment includes a shape memory spring strut havinga first end and a second end wherein the shape memory spring strut isextendable from a first length to a second length and the shape memoryspring strut contains a shape memory alloy. This embodiment alsoincludes a shape memory spring strut activation line connected to theshape memory spring strut wherein the shape memory spring strutactivation line may be configured to activate the shape memory springstrut and a longitudinal connecting member having a first segment and asecond segment wherein the first segment is in pivotal contact with thefirst end of the shape memory spring strut and the second segmentsupports a wheel rotatably mounted on a pin. The connecting member maybe moveable along a line of travel from an extended position to aretracted position in this embodiment.

[0007] In a second embodiment a method of retracting aircraft landinggear is provided. This method comprises activating a shape memory alloywithin a shape memory spring strut wherein the shape memory alloy isactivated via a shape memory spring strut activation line in contactwith the shape memory spring strut, the shape memory spring strut havinga first end and a second end and being extendable from a first length toa second length.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1a shows a first view of an exemplary shape memory spring(SMS) according to the present invention.

[0009]FIG. 1b shows a first view of an exemplary shape memory spring(SMS) according to the present invention.

[0010]FIG. 2 shows a first view of an exemplary heat converter engineaccording to the present invention.

[0011]FIG. 3 shows a second view of an exemplary heat converter engineaccording to the present invention.

[0012]FIG. 4 shows a third view of an exemplary heat converter engineaccording to the present invention.

[0013]FIG. 5 shows a top view of an exemplary conveyor belt system for aheat converter engine according to the present invention.

[0014]FIG. 6 shows an exemplary SMS assembly for a heat converter engineaccording to the present invention.

[0015]FIG. 7 shows a detail view of an exemplary SMS assembly coupled toexemplary crank shafts in a heat converter engine according to thepresent invention.

[0016]FIG. 8 shows an exemplary system for powering a conveyor system ina heat converter engine according to the present invention.

[0017]FIG. 9 shows an exemplary system for derailing an SMS assemblycoupled to crank shafts in a heat converter engine according to thepresent invention.

[0018]FIG. 10 shows a front view of a heat converter engine according tothe present invention.

[0019]FIG. 11 shows an exemplary manner of applying a heating andcooling medium to a heat converter engine according to the presentinvention.

[0020]FIG. 12 shows an exemplary heat converter engine of the presentinvention as an alternative power source for mechanisms in anautomobile.

[0021]FIG. 13 shows an alternative embodiment of a crank shaft for aheat converter engine according to the present invention.

[0022]FIG. 14a shows a time versus speed curve for an exemplary heatconverter engine having a substantially circular crank shaft accordingto the present invention.

[0023]FIG. 14b shows a time versus speed curve for an exemplary heatconverter engine having an alternatively shaped crank shaft according tothe present invention.

[0024]FIG. 15 shows an exemplary link of a flexible crank shaft for aheat converter engine according to the present invention.

[0025]FIG. 16 shows an exemplary manner of coupling an exemplary SMSassembly to an exemplary link of a flexible crank shaft for a heatconverter engine according to the present invention.

[0026]FIG. 17 shows an alternative embodiment of a heat converter engineaccording to the present invention.

[0027]FIG. 18 shows an alternative embodiment wherein a heat converterengine according to the present invention may be used as an electricgenerator.

[0028]FIG. 19 shows an exemplary embodiment of an alternative actuatorassembly for a heat converter engine according to the present invention.

[0029]FIG. 20a shows a first view of an exemplary actuator arm of anexemplary embodiment of an actuator assembly for a heat converter engineaccording to the present invention.

[0030]FIG. 20b shows a second view of an exemplary actuator arm of anexemplary embodiment of an actuator assembly for a heat converter engineaccording to the present invention.

[0031]FIG. 21a shows a first exemplary embodiment of a hub and spokeassembly of an actuator assembly for a heat converter engine accordingto the present invention.

[0032]FIG. 21b shows a second exemplary embodiment of a hub and spokeassembly of an actuator assembly for a heat converter engine accordingto the present invention.

[0033]FIG. 22a shows a first exemplary embodiment of an actuator arm ofan actuator assembly for a heat converter engine according to thepresent invention.

[0034]FIG. 22b shows a second exemplary embodiment of an actuator arm ofan actuator assembly for a heat converter engine according to thepresent invention.

[0035]FIG. 23 shows a detail view of an actuator assembly according tothe present invention.

[0036]FIG. 24 shows an exemplary embodiment of a heat converter enginepowered by an actuator assembly according to the present invention.

[0037]FIG. 25 shows a detail view of an exemplary actuator arm from anexemplary embodiment of a heat converter engine powered by an actuatorassembly according to the present invention.

[0038]FIG. 26 shows an exemplary embodiment of an actuator assembly anda main case from an exemplary embodiment of a heat converter engineaccording to the present invention.

[0039]FIG. 27 shows an exemplary embodiment of a system for heating aheating medium to be used in the present invention.

[0040]FIG. 28 shows a second exemplary embodiment of an actuatorassembly according to the present invention.

[0041]FIG. 29 shows an aircraft landing gear in an extended position inaccordance with an alternative embodiment of the present invention.

[0042]FIG. 30 shows an aircraft landing gear in a semi-extended positionin accordance with an alternative embodiment of the present invention.

[0043]FIG. 31 shows an aircraft landing gear in a retracted position inaccordance with an alternative embodiment of the present invention.

[0044]FIG. 32 shows an airplane landing gear in an extended position inaccordance with an alternative embodiment of the present invention.

[0045]FIG. 33 shows an aircraft landing gear in an extended positionunder static load in accordance with an alternative embodiment of thepresent invention.

[0046]FIG. 34 shows an aircraft landing gear in an extended airborneposition in accordance with an alternative embodiment of the presentinvention.

[0047]FIG. 35 shows an aircraft landing gear in a semi-extended positionin accordance with an alternative embodiment of the present invention.

[0048]FIG. 36 shows an aircraft landing gear in a retracted position inaccordance with an alternative embodiment of the present invention.

[0049]FIG. 37 shows a motor vehicle wiper arm and identifies theenlarged area seen in FIGS. 38 and 39.

[0050]FIG. 38 shows an enlarged view of one end of a motor vehicle wiperarm in a relaxed state in accordance with an alternative embodiment ofthe present invention.

[0051]FIG. 39 shows an enlarged view of one end of a motor vehicle wiperarm in a compressed state in accordance with an alternative embodimentof the present invention.

[0052]FIG. 40 shows a motor vehicle wiper arm in accordance with analternative embodiment of the present invention.

[0053]FIG. 41 shows a locking assembly in accordance with an alternativeembodiment of the present invention.

[0054]FIG. 42 shows a locking assembly in accordance with an alternativeembodiment of the present invention.

[0055]FIG. 43 shows a solar array mounted to shape memory alloy supportsin accordance with an alternative embodiment of the present invention.

[0056]FIG. 44 shows a solar array mounted to shape memory alloy supportsin accordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION

[0057] The present invention may be further understood with reference tothe following description and the appended drawings, wherein likeelements are provided with the same reference numerals. FIGS. 1a-b showa shape memory spring (SMS) 10 constructed of a shape memory alloy(SMA), for example, Nitinol. As described above, when an SMA is belowits critical temperature, it becomes malleable and may be deformed intoany shape. However, when the SMA is heated above its criticaltemperature the alloy undergoes a temperature related phase changeallowing it to return to the mechanical configuration imposed on thematerial when it was annealed. FIG. 1a shows SMS 10 in its originalcompressed shape, i.e., above the SMAs critical temperature. Therefore,when the SMA of SMS 10 is heated above its critical temperature, SMS 10returns to the compressed state as illustrated in FIG. 1a. FIG. 1b showsSMS 10 when the SMA is below its critical temperature. Because the SMAis malleable below its critical temperature, SMS 10 may be stretched,increasing its length. The purpose of this particular deformation willbe described in greater detail below. Those skilled in the art willunderstand that this deformation is only exemplary and that it is alsopossible to anneal SMS 10 so that the stretched state is the originalstate and SMS 10 may be compressed when the SMA is malleable.

[0058]FIG. 2 shows inner crank shaft carrier 20, outer crank shaftcarrier 30, inner derail 40 and outer derail 50 according to a firstembodiment of heat converter engine 15 of the present invention. Outercrank shaft carrier 30 is substantially cylindrical having raised walls31 and 32 which form channel 33 around the circular perimeter of outercrank shaft carrier 30. Outer derail 50 is integrally connected to outercrank shaft carrier 30 such that raised wall 31 continues around theoutside perimeter of outer derail 50. Outer derail 50 also has raisedwall 51, which, along with raised wall 31 forms channel 53 in outerderail 50. Channel 33 of outer crank shaft carrier 30 and channel 53 ofouter derail 50 form a single continuous channel through outer crankshaft carrier 30 and outer derail 50. The purpose of this continuouschannel will be described in greater detail below. Inner crank shaftcarrier 20 is substantially similar in shape to outer crank shaftcarrier 30, including having channel 23. Inner crank shaft carrier 20 issmaller and fits inside the hollow center of outer crank shaft carrier30. Inner derail 40 is substantially similar in shape to outer derail50, including having channel 43. When inner crank shaft carrier 20 isplaced inside outer crank shaft carrier 30 the inner derail 40 and outerderail 50 should be aligned so that channel 43 is substantially parallelto channel 53. Those skilled in the art will understand that thearrangement of heat converter engine 15 shown in FIG. 2 is onlyexemplary and that there are other arrangements for the elements shownin this figure. For example, channel 43 of inner derail 40 may bearranged so that it faces inward towards axis 25 of inner crank shaftcarrier 20 and opposes channel 53 of outer derail 50. In thisarrangement, channel 23 may be formed on the inside surface of the outerperimeter of inner crank shaft carrier 20 so that channel 23 and channel43 form a continuous channel.

[0059]FIG. 3 shows inner crank shaft 60 located on inner crank shaftcarrier 20 and outer crank shaft 70 located on outer crank shaft carrier30 added to heat converter engine 15. Inner crank shaft 60 and outercrank shaft 70 are mounted on their respective crank shaft carriers 20and 30 so they may rotate freely. Those skilled in the art willunderstand that there are numerous manners of mounting crank shafts 60and 70 to crank shaft carriers 20 and 30. FIG. 3 also shows anotherfeature of interest in outer crank shaft carrier 30 and outer derail 50.Slit 34 runs along the entire length of channel 33 in outer crank shaftcarrier 30 and slit 54 runs along the entire length of channel 53 inouter derail 50. The purpose of slits 34 and 54 will be described ingreater detail below.

[0060]FIG. 4 shows additional components added to heat converter engine15, including SMS 10 (shown in sketch form as bars), outer SMS carriers90 and conveyor belt 100 which is coupled to conveyor belt gears 110 and115. The number of outer SMS carriers 90 shown in FIG. 4 is onlyexemplary and it should be understood that there is an outer SMS carrier90 corresponding to each SMS 10 in heat converter engine 15. Conveyorbelt 100 is driven by conveyor belt gear 110 in the direction of arrow116 and continuously loops around conveyor belt gears 110 and 115. Themechanism to drive conveyor belt gear 110 will be described in greaterdetail below. FIG. 5 shows a top view of conveyor belt 100 which hasflat inner surface 101 that comes in contact with conveyor belt gears110 and 115 and ribbed outer surface 102. Ribs 103 form pockets 104 onribbed outer surface 102. Referring back to FIG. 4, wheels 91 of outerSMS carriers 90 engage in pockets 104 of conveyor 100 as SMS carriersenter outer derail 50, thereby coupling outer SMS carriers 90 toconveyor belt 100. The coupling of outer SMS carriers 90 to conveyorbelt 100 also causes outer SMS carriers 90 to move through channel 53 ofouter derail 50 in the direction of arrow 116. Those skilled in the artwill understand that SMS carriers 90 may be coupled in other manners toconveyor 100 in such a way that the rotation of conveyor 100 is impartedto SMS carriers 90. Those skilled in the art will also understand thatthere is a corresponding conveyor belt and inner SMS carriers (notshown) that move in the same direction through channel 43 of innerderail 40.

[0061]FIG. 6 shows a detail view of SMS 10, outer SMS carrier 90 andinner SMS carrier 120. Inner SMS carrier 120 has wheels 121, pin guide122 and hook 123. Similarly outer SMS carrier 90 has wheels 91, pinguide 92, wedge guide 93 and a hook (not shown). First end 11 of SMS 10is connected to hook 123 of inner SMS carrier 120 and second end 12 ofSMS 10 is connected to a hook (not shown) of outer SMS carrier 90creating SMS assembly 130. As described with reference to FIG. 3, outercrank shaft carrier 30 and outer derail 50 may have slits 34 and 54,respectively. The purpose of slits 34 and 54 is that as outer SMScarrier 90 of SMS assembly 130 moves through channels 33 and 53, SMS 10of SMS assembly 130 may project through slits 34 and 54. Similarly,channels 23 and 43 may also have slits for the projection of SMS 10, ifchannels 23 and 43 are arranged to oppose channels 33 and 53. Throughoutthe figures outer and inner SMS carriers 90 and 120 are shown withvarying numbers of wheels. Those skilled in the art will understand thatthe number of wheels is not important and the purpose of the wheels isto allow the carriers to move freely through the channels.

[0062]FIG. 7 shows an exemplary manner of coupling SMS assembly 130 toinner crank shaft 60 and outer crank shaft 70. Inner crank shaft 60 hasslot 61 which engages pin guide 122 of inner SMS carrier 120. Similarly,outer crank shaft 70 has slot 71 which engages pin guide 92 of outer SMScarrier 90. The purpose of wedge guide 93 will be described in greaterdetail below. When inner SMS carrier 120 is engaged with inner crankshaft 60 and outer SMS carrier 90 is engaged with outer crank shaft 70,SMS assembly 130 is coupled to crank shafts 60 and 70. Thus, as crankshafts 60 and 70 rotate about their respective carriers 20 and 30, SMSassembly 130 also rotates. As will be described in greater detail below,the action of the SMS assemblies causes the crank shafts to rotate.Those skilled in the art will understand that there are numerous mannersof coupling SMS assembly 130 to crank shafts 60 and 70 and the abovedescribed manner is only exemplary. It should also be understood thatcrank shafts 60 and 70 may have numerous slots 61 and 71 located aroundthe entire circumference of each crank shaft so that any number of SMSassemblies 130 may be engaged at any particular time. Also, in FIG. 7,pin guide 122 is shown on the top of inner SMS carrier 120, whereas inFIG. 6, pin guide 122 is shown on the bottom of inner SMS carrier 120.As described above, there are numerous possible arrangements for theelements of heat converter engine 15 and whether inner SMS carrier 120is located inside or outside inner crank shaft 60 determines thelocation of guide 122.

[0063]FIG. 8 shows a cross-section of heat converter engine 15 showing aside view of inner crank shaft carrier 20, outer crank shaft carrier 30and the derailing area. This figure shows an exemplary arrangement fordriving outer conveyor belt 100 located in outer derail 50 and innerconveyor belt 105 located in inner derail 40. Gear 160 is coupled toinner crank shaft 60 (not shown) in any number of known manners, forexample, a rotor may be attached to inner crank shaft 60 to impartrotational movement to gear 160. The coupling of gear 160 to gear 161imparts the rotation of inner crank shaft 60 to shaft 165 connected togear 161. The rotation of shaft 165 is imparted to conveyor belts 100and 105 through conveyor belt gears 110 and 111 which are coupled toshaft 165. Those skilled in the art will understand that gears 160 and161 may be selected to control the speed that SMS assemblies 130 movethrough the inner and outer derails 40 and 50 relative to the rotationalspeed of inner crank shaft 60. The speed that SMS assemblies 130 movethrough inner and outer derails 40 and 50 may be determined by numerousfactors including the alloy used for the SMS assembly, the cooling rateof the cooling medium, the length of the derail area, etc.

[0064]FIG. 9 shows an exemplary manner of derailing SMS assembly 130from inner crank shaft 60 and outer crank shaft 70. Derailer 170includes shaft 172 connected to outer derailing wheel 171 and innerderailing wheel 173. In FIG. 9, derailer 170 is shown offset from innerand outer crank shafts 60 and 70 for illustration purposes. Inoperation, derailer 170 is within the boundaries of inner and outercrank shafts 60 and 70 so that outer and inner derailing wheels 171 and173 may engage pin guides 92 and 122 of outer and inner SMS carriers 90and 120, respectively. The operation of derailer 170 will be describedin reference to the derailment of outer SMS carrier 90, however, itshould be understood that the operation is similar for the derailment ofinner SMS carrier 120. Derailer 170 rotates about vertical axis 174 asthe portion of inner and outer crank shafts 60 and 70 coupled to SMSassembly 130 move towards derailer 170. Pin guide 92 of outer SMScarrier 90 comes into contact with outer derailing wheel 171 of derailer170. The rotation of derailer 170 pushes pin guide 92 out of slot 71 ofouter crank shaft 70 causing SMS assembly 130 to become decoupled fromouter crank shaft 70. Those skilled in the art will understand that theshape of outer and inner derailing wheels 171 and 173 and the directionof rotation of derailer 170 is not important. The purpose of derailer170 is to engage outer and inner SMS carriers 90 and 120 and decouplethem from inner and outer crank shafts 60 and 70. Any known mechanicalor electrical means may be used to control the rotation of derailer 170.The conveyor system and derailing operations described above may betimed with the rotation of the inner and outer crank shafts 60 and 70(the heat converter engines RPM).

[0065] An exemplary manner of operating heat converter engine 15 will bedescribed in more detail with reference to FIGS. 4 and 10. FIG. 10 showsa front view cross-section of heat converter engine 15 showing SMSassemblies 130 a-g, inner crank shaft 60 and outer crank shaft 70. Therotation of crank shafts 60 and 70 coupled to SMS assemblies 130 a-gwill be described in more detail with reference to an exemplary SMSassembly. The exemplary SMS assembly may be considered to start at theposition of SMS assembly 130 a, where it has been previously heatedabove the critical temperature of the SMA and is in its originalcompressed state. Inner derail 40 and outer derail 50 (not shown) arelocated between the position of SMS assemblies 130 a and 130 b. Thus, asdescribed above, the exemplary SMS assembly may be decoupled or derailedfrom inner crank shaft 60 and outer crank shaft 70 into inner derail 40and outer derail 50 between the positions of SMS assemblies 130 a and130 b. As the exemplary SMS assembly travels through the inner and outerderails 40 and 50, the exemplary SMS assembly is cooled below itscritical temperature and becomes malleable, allowing the SMS to bestretched. The cooled exemplary SMS assembly leaves the inner and outerderails 40 and 50 and re-couples with crank shafts 60 and 70 in theposition of SMS assembly 130 b. As shown in FIG. 10, the exemplary SMSassembly in the position of SMS assembly 130 b has become stretched withrespect to the original length of the SMS shown in the position of SMSassembly 130 a. As crank shafts 60 and 70 continue to rotate in thedirection of arrow 135, the exemplary SMS assembly rotates through thepositions of SMS assemblies 130 c and 130 d where the SMS becomesprogressively longer or more stretched because it remains in itsmalleable state. At a predefined position of the rotation, a heatingmedium will begin to heat the SMS of the exemplary SMS assembly. Thepredetermined position for application of the heating medium may bedetermined by a variety of factors including the alloy used for the SMS,the heat transfer rate of the heating medium, the speed of rotation,etc. As crank shafts 60 and 70 continue to rotate in the direction ofarrow 135, the exemplary SMS assembly is heated above its criticaltemperature and begins to regain its original shape. The beginning ofcompression is when the exemplary SMS assembly is in the position of SMSassembly 130 e. The action of the SMS assembly resuming its originalshape causes a force to be exerted in the radial direction, which, inturn, causes inner crank shaft 60 and outer crank shaft 70 to rotate.Finally, as crank shafts 60 and 70 continue to rotate, the exemplary SMSassembly continues to resume its original shape as it is rotated throughthe positions of SMS assemblies 130 f and 130 g until it fully regainsits original compressed state in the position of SMS assembly 130 a.Thus, rotation of crank shafts 60 and 70 is accomplished by continuousheating and cooling of the SMS assemblies, where the force of the SMSassemblies returning to their original shape causes the crank shafts torotate. Because each of the SMS assemblies 130 a-g are in various statesof compression, inner crank shaft 60 will not be concentric with outercrank shaft 70. However, those skilled in the art will recognize thatinner crank shaft 60, while not centered within outer crank shaft 70,will remain at a fixed position relative to outer crank shaft 70.

[0066] Referring back to FIG. 4, a more detailed description of thetravel of the exemplary SMS assembly through the derail area will beprovided. As described above, the exemplary SMS assembly may bedecoupled from the inner and outer crank shafts 60 and 70 by thederailer (not shown) when the exemplary SMS assembly has been heated andregained its original compressed shape. As the exemplary SMS assemblyenters the derail area, outer SMS carrier 90 may be coupled to conveyorbelt 100 and inner SMS carrier (not shown) may be coupled to theconveyor belt in inner derail 40. Also as described above, the conveyorbelts rotate in the direction of arrow 115 and the exemplary SMSassembly rotates through channels 43 and 53 when it is coupled to theconveyor belts. A cooling medium is applied to the exemplary SMSassembly as it travels through the derail area to cool the SMA alloybelow the critical temperature so SMS 10 becomes malleable. Thoseskilled in the art will understand that the exemplary SMS assembly maybegin to stretch as it travels through the derail area because thedistance between crank shafts 60 and 70 at the location where theexemplary SMS assembly is re-coupled to crank shafts 60 and 70 isgreater than the location where the exemplary SMS assembly is decoupledfrom crank shafts 60 and 70. The decoupling of the heated SMS assembliesfrom crank shafts 60 and 70 to be cooled in the derail area eliminatesresistance against the SMS assemblies that are being heated andcompressing as described above with reference to FIG. 10. Theelimination of this resistance results in a more powerful and efficientheat convertor engine.

[0067]FIG. 11 shows the relative positions of the application of theheating and cooling mediums to heat converter engine 15. As describedabove, cooling medium 140 may be applied to the SMS assemblies (notshown) when they are located in the area of inner derail 40 and outerderail 50. Similarly, heating medium 150 may be applied to the SMSassemblies at a predetermined position when the SMS assemblies arecoupled to crank shafts 60 and 70. Those skilled in the art willunderstand that any gas or liquid may be used to heat or cool the SMSassemblies, for example, air, water or a refrigerant may be used.Likewise, the heating or cooling medium may be contained in either anopen system, where the heating or cooling medium is exhausted directlyinto the atmosphere, or in a closed system, where the heating or coolingmedium may be recycled through the system. Also, the transfer of heatbetween the mediums and the SMS assemblies may be direct or indirect,for example, through a heat exchanger.

[0068]FIG. 12 shows an exemplary use of a heat converter engine of thepresent invention as an alternative power source for mechanisms in anautomobile. The use of a heat converter engine in on automobile may beadvantageous because a heating medium (heated exhaust gas) and a coolingmedium (air flow from the fan) are readily available. For example, innercrank shaft 60 may be coupled to drive shaft 65 which, in turn, iscoupled to shaft 181 of transmission 180. Rotor 182 of transmission 180may be coupled to pulley mechanism 200 which is connected to a series ofdrive belts 201-203. First drive belt 201 may be coupled to alternator210, second drive belt 202 may be coupled to power steering pump 220,and third drive belt 203 may be coupled to air conditioning unit 230. Asdescribed above with reference to FIGS. 4 and 10, by heating and coolingSMS assemblies 130 of heat converter engine 15, it is possible to causedrive shaft 65, shaft space 181 and rotor 182 to rotate. The rotation ofrotor 182 may cause pulley 200 to rotate and this rotation may beimparted to each of alternator 210, power steering pump 220 and airconditioning unit 230 by drive belts 201-203, respectively. Thus, theheat converter engine may be used as an alternative power source forthese devices, resulting in lowering the load on the internal combustionengine of the automobile and causing an increase in efficiency. Otherexamples of devices in an automobile that may be powered by thisalternative power source may be water pumps, fuel pumps, etc. Thoseskilled in the art will understand that the pulley and drive belt systemdescribed is only exemplary, and that depending upon the application, adifferential or other similar gearing may be used to impart the correctamount of power to the device using the alternative power source.Additionally, this alternative power source is not limited to automobileor motor vehicle applications, it may be used in any situation where adevice may be powered by imparting mechanical rotation to the enddevice, or it may be used to power a generator which may produceelectrical power for any consumption device. Other examples ofsituations where heating and cooling mediums exist are natural hotsprings or power plants where cooling water is used to cool the plantscomponents.

[0069]FIG. 13 shows an alternative embodiment for outer crank shaftcarrier 240 and outer crank shaft 250. In this embodiment, outer crankshaft carrier 240 has a substantially straight section 241 connected toan arc-shaped section 242, and outer crank shaft 250 is flexible torotate about outer crank shaft carrier 240. Note that the derail portionof the heat converter engine is not shown in FIG. 13. FIG. 17 shows anexample of a heat converter engine including outer crank shaft carrier240 and the derail area. A plurality of links 260 are coupled to formflexible outer crank shaft 250. The remaining elements and operation ofa heat converter engine having outer crank shaft carrier 240 andflexible outer crank shaft 250 are the same as those described above.The shape of outer crank shaft carrier 240 allows the flexible outercrank shaft 250 to rotate faster and have a more constant RPM. Forexample, FIG. 14a shows a time versus speed curve for a heat converterengine having a substantially circular outer crank shaft carrier andouter crank shaft as described with reference to FIG. 3. Whereas, FIG.14b shows a time versus speed curve for a heat converter engine havingthe shape of outer crank shaft carrier 240 and flexible outer crankshaft 250. As shown by these curves, a heat converter engine with theouter crank shaft carrier shaped in the form of outer crank shaftcarrier 240 produces higher speeds in a shorter amount of time andprovides a more linear time versus speed characteristic. Those skilledin the art will understand that each of these designs may be moreefficient for any number of applications and the particular type ofcrank shaft will be determined by the application.

[0070]FIG. 15 shows a detail view of exemplary links 260 of flexibleouter crank shaft 250. Each link 260 has first end 261, second end 262and middle section 263. First end 261 has a substantially cylindricalsection 264 which has hollow center 267. Two arc-shaped surfaces 265 and266 formed in middle section 263 are adjacent to cylindrical section 264and have substantially the same curvature as cylindrical section 264.Second end 262 has two substantially cylindrical sections 268 and 269which have hollow centers 268 and 269, a respectively. Arc-shapedsurface 273 formed in middle section 263 is between cylindrical sections271 and 272 and has substantially the same curvature as cylindricalsections 271 and 272. Slot 275 is formed in middle section 263 and willbe described in greater detail below. Links 260 may be coupled byinserting cylindrical section 264 of first end 261 into arc shapedsurface 273 of second end 262. This insertion also causes cylindricalsections 268 and 269 of second end 262 to be inserted in arc shapedsurfaces 265 and 266 of first end 261. The result of this insertion isthat hollow centers 267, 271 and 272 of cylindrical sections 264, 268and 269, respectively, form a continuous via through links 260 with asubstantially uniform diameter. Connection pin 680 may be inserted intothe via to couple links 260. A plurality of links 260 may be coupled toform flexible outer crank shaft 250.

[0071]FIG. 16 shows a detail view of exemplary link 260 coupled to outerSMS carrier 90. Link 260 has slot 275 which is a cut out having twosubstantially straight sections connected by an arc shaped sectionrunning from the top to the bottom of link 260. At a predetermineddistance from the top, the diameter of slot 275 is narrowed causing aridge 276 to be formed in slot 275. Ridge 276 is closer to the top atthe edge of slot 275 and tapers to be farther away from the top as itnears the arc section of slot 275. Outer SMS carrier 90 has pin guide 92and wedge guide 93. Wedge guide 93 has substantially the same shape asslot 275 and is also tapered to widen in the arc section. As SMS carrier90 is engaged in link 260, wedge guide 93 is seated on ridge 276 of slot275 until the bottom of the arc section of wedge guide 93 comes intocontact with the arc section of slot 275, coupling SMS carrier 90 tolink 260. In this manner, SMS assemblies may be coupled to the outercrank shaft in heat converter engines having the shape described forouter crank shaft carrier 240 with reference to FIG. 13.

[0072]FIG. 17 shows an exemplary embodiment of a heat converter enginethat has storage areas 300 and 310 for broken SMS assemblies andreplacement SMS assemblies. The features of the exemplary heat converterengine are the same as described above, except that inner and outerderails 40 and 50 have additional storage areas 300 and 310. (Storagearea 310 of inner derail 40 is not shown). Storage areas 300 and 310form additional channels through which SMS assemblies may be moved.Sensor 290 senses whether an SMS assembly is in disrepair, for example,a broken SMS or carrier. Those skilled in the art will understand thatthere are numerous types of sensors that may be configured to detect abroken SMS or carrier, for example, a load sensor such as a springloaded switch or a light beam sensor. When sensor 290 determines that anSMS assembly is in disrepair, it may send a signal to a derailer toderail the broken SMS assembly from outer and inner derail 40 and 50into storage area 300 in the direction of arrow 301. Those skilled inthe art will understand that a derailer similar to the one describedabove may be used for this purpose. New SMS assemblies may be stored instorage area 310, and when a broken SMS assembly is removed from outerand inner derail 40 and 50, a new SMS assembly from storage area 310 maymove into the position voided by the broken spring. The new SMS assemblymay move into outer and inner derail 40 and 50 in the direction ofarrows 311. Those skilled in the art will understand that there arenumerous methods of controlling the timing of moving the new SMSassembly into the position voided by the broken SMS assembly.

[0073]FIG. 18 shows an exemplary arrangement wherein a heat converterengine may operate as a generator or alternator. SMS assembly 130 isshown having SMS 10, outer SMS carrier 90 and inner SMS carrier 120.Outer SMS carrier 90 has wheels 96 and 97 which are constructed of amagnetic material, where wheel 96 has the opposite polarity of wheel 97.Similarly, inner SMS carrier 120 has wheels 126 and 127 constructed of amagnetic material, where wheel 126 has the opposite polarity of wheel127. Inner crank shaft carrier 20 has coil 26 and outer crank shaftcarrier 30 has coil 36. SMS assembly 130 travels through inner crankshaft carrier 20 and outer crank shaft carrier 30 which are bothstationary. As the magnetic wheels of the outer and inner SMS carriers90 and 120 pass through coils 26 and 36 of inner and outer crank shaftcarriers 20 and 30, the movement induces a current to flow in coils 26and 36. Thus, a heat converter engine rather than powering anautomobiles alternator as described with respect to FIG. 12 may alsoserve as the alternator for an automobile. Alternative Embodiments: FIG.19 shows an actuator assembly 401 according to a first alternativeembodiment of the present invention, which includes a hub and spokeassembly 402 having hub 403 and circular spokes 404-409, and actuatorarms 414-419. At least a portion of actuator arms 414-419 of actuatorassembly 401 are constructed of a shape memory alloy (SMA), for example,Nitinol. Hub and spoke assembly 402 of actuator assembly 401 may beconsidered a crank shaft and may be constructed from any suitablematerial that is not an SMA, for example, metal, plastic, or rubber.Actuator assembly 401 may rotate about axis 420 of hub 403 in eitherdirection as shown by arrow 421. The purpose of rotating actuatorassembly 401 will be described in greater detail below. Those skilled inthe art will understand that the number of spokes and actuator armsshown in FIG. 19 are only exemplary and that there may be any number ofspokes and actuator arms based on the particular application intendedfor the actuator assembly.

[0074]FIGS. 20a-b show two different views of an exemplary actuator armof actuator assembly 401 from FIG. 19, for example, actuator arm 414which is constructed of an SMA. As described above, when an SMA is belowits critical temperature, it becomes malleable and may be deformed intoany shape. However, when the SMA is heated above its criticaltemperature the alloy undergoes a temperature related phase changeallowing it to return to the mechanical configuration imposed on thematerial when it was annealed. FIG. 20a shows exemplary actuator arm 414in its original shape, i.e., above the SMAs critical temperature. InFIG. 20a, exemplary actuator arm 414 has a first end 430 connected tosecond end 431 by a substantially straight middle section 432.Therefore, when the SMA of exemplary actuator arm 414 is heated aboveits critical temperature, actuator arm 414 returns to the shapeillustrated in FIG. 20a. FIG. 20b shows exemplary actuator arm 414 whenthe SMA is below its critical temperature. Because the SMA is malleablebelow its critical temperature, actuator arm 414 may deform into someother shape. For example, in FIG. 20b, middle section 432 is shown asdeformed into a curved shape. Those skilled in the art will understandthat this deformation is only exemplary and that when the SMA ismalleable any portion of actuator arm 414 may be deformed depending onthe forces acting upon actuator arm 414. The purpose of this particulardeformation will be described in greater detail below. Additionally, asshown in FIGS. 20a and 20 b, the entire exemplary actuator arm 414 isconstructed of an SMA. Depending on the particular purpose and use ofthe actuator arm, it may be possible to construct only a portion ofactuator arm 414 of SMA. For example, if the only deformation requiredof actuator arm 414 is that shown in FIG. 20b, it may be possible toonly construct middle section 432 of an SMA and first end 430 and secondend 431 of some other material.

[0075]FIG. 21a shows a first exemplary embodiment of hub and spokeassembly 402 of actuator assembly 401 from FIG. 19. FIG. 21a shows asectional view of hub 403 and spokes 404, 405 and 409. The features ofthe spokes will be described with respect to spoke 409, but thesefeatures are typical for all the spokes. Spoke 404 has a generallycylindrical shape with a solid first end and an open second end which isan intake port 441 leading to hollow inside cavity 450. Wall 445 ofspoke 404 is preferably formed as a generally cylindrical surface exceptfor a feature of interest in the present invention. Exhaust port 442 inwall 445 provides a via from hollow cavity 450 to outside of spoke 404.Intake port 441 and exhaust port 442 may be used to conduct the flow ofgas or fluid heating and/or cooling mediums to the actuator arms. Intakeport 441 has a generally circular shape and exhaust port 442 has agenerally rectangular shape. However, the shape of intake port 441 andexhaust port 442 is not critical, as there may be different optimumshapes for various heating and cooling mediums. As will be described ingreater detail below, an intake port of an actuator arm may bepositioned adjacent to exhaust port 442 so the flow of the heating orcooling medium may enter the actuator arm as it leaves spoke 404. Forexample, hot air may flow into spoke 409 through intake port 441 in thedirection of arrow 451 into hollow inside cavity 450 and out exhaustport 442 in the direction of arrow 452. Those skilled in the art willunderstand that any gas or liquid may be used to heat or cool theactuator arms. For example, in addition to air, water or a refrigerantmay be used.

[0076]FIG. 22a shows a first exemplary embodiment of an exemplaryactuator arm of actuator assembly 401 from FIG. 19, for example,actuator arm 414. This embodiment of actuator arm 414 may be used inconjunction with the exemplary hub and spoke assembly 402 described withreference to FIG. 21a. As described above, actuator arm 414 isconstructed of an SMA and has a first end 430 connected to a second end431 by middle section 432. First end 430 has intake port 460 which hasthe same general shape as exhaust port 442 of spoke 404 described withreference to FIG. 21a. When actuator arm 414 is positioned inconjunction with hub and spoke assembly 402, intake port 460 is adjacentto exhaust port 442 of spoke 404. Actuator arm 414 has hollow channel461 leading from intake port 460 through the entire length of middlesection 432 to exhaust port 462 in second end 431. Intake port 460,hollow channel 461 and exhaust port 462 allow the heating or coolingmedium from hub and spoke assembly 402 to flow through the entire insidelength of actuator arm 414 so that the SMA of actuator arm 414 isuniformly heated or cooled. For example, the hot air flow describedabove, may leave spoke 409 through exhaust port 442 and enter actuatorarm 414 through intake port 460 in the direction of arrow 465, flowthrough hollow channel 461 heating the SMA to above the criticaltemperature, causing actuator arm 414 to return to its original shape.The hot air may continue to flow through exhaust port 462 in thedirection of arrow 466 to exit actuator arm 414. Similarly, any coolingmedium may also be used to cool actuator arm 414 to below its criticaltemperature so that it becomes malleable. Those skilled in the art willunderstand that the heating or cooling medium may be contained in eitheran open system, where the heating or cooling medium is exhausteddirectly into the atmosphere, or in a closed system, where the heatingor cooling medium may be recycled through the system.

[0077]FIG. 21b shows a second exemplary embodiment of hub and spokeassembly 402 of actuator assembly 401 from FIG. 19. FIG. 21b shows asectional view of hub 403 and spokes 404, 405 and 409. The features ofthe spokes will be described with respect to spoke 404, but thesefeatures are typical for all the spokes. Spoke 404 has a generallycylindrical shape with intake port 471 in a first end which leads tofirst hollow cavity 473 and exhaust port 472 in a second end which leadsto a second hollow cavity 474. First hollow cavity 473 is separated fromsecond hollow cavity 474 by a solid wall (not shown) that prevents anydirect flow of heating or cooling medium between these cavities. Wall475 of spoke 404 is preferably formed as a generally cylindrical surfaceexcept for two features of interest in the present invention. Firstintermediate port 476 provides a via from first hollow cavity 473 tooutside of spoke 404 and second intermediate port 477 provides a viafrom second hollow cavity 474 to outside of spoke 404. Intake port 471,first intermediate port 476, second intermediate 477 and exhaust port472 may be used to conduct the flow of a heating or cooling medium toand from the actuator arms of the actuator assembly. As described above,the shape of ports 471, 472, 476 and 477 is not critical, as there maybe different optimum shapes depending on the particular heating orcooling medium. As will be described in greater detail below, two portsof an actuator arm may be positioned adjacent to first intermediate port476 and second intermediate port 477 so that the flow of the heating orcooling medium may enter and exit the actuator arm. For example, hot airmay flow into spoke 409 through intake port 471 in the direction ofarrow 481 into first hollow cavity 473 and then out first intermediateport 476 in the direction of arrow 482. When the flow leaves firstintermediate port 476 it enters a port of an actuator arm that isadjacent to first intermediate port 476. The flow of the heating orcooling medium through the actuator arm will be described in greaterdetail below. The flow leaves the actuator arm through a port that ispositioned adjacent to second intermediate port 477. The flow leavingthe actuator arm will enter second intermediate port 477 in thedirection of arrow 483 into second hollow cavity 474 and out of spoke404 through exhaust port 472 in the direction of arrow 484.

[0078]FIG. 22b shows a second exemplary embodiment of an exemplaryactuator arm of actuator assembly 401 from FIG. 19, for example,actuator arm 414. This embodiment of actuator arm 414 may be used inconjunction with the exemplary hub and spoke assembly 402 described withreference to FIG. 21b. As described above, actuator arm 414 isconstructed of an SMA and has first end 430 connected to second end 431by middle section 432. First end 430 has intake port 490 which has thesame general shape as first intermediate port 476 of spoke 404, asdescribed with reference to FIG. 4b. First end 430 also has exhaust port491 which has the same general shape as second intermediate port 477 ofspoke 404, as described with reference to FIG. 21b. When actuator arm414 is positioned in conjunction with hub and spoke assembly 402, intakeport 490 is adjacent to first intermediate port 476 of spoke 404 andexhaust port 491 is adjacent to second intermediate port 477. Actuatorarm 414 has a hollow channel 493 which has a first section 501 runningfrom intake port 490 through middle section 432 towards second end 431.Prior to entering second end 431, hollow channel 493 has a secondsection 502 that is at substantially a right angle to first section 501.A third section 503 of hollow channel 493 is at substantially a rightangle to second section 502 and runs to exhaust port 491. Those skilledin the art will understand that the shape of hollow channel 493 is notimportant, the importance of hollow channel 493 is that it delivers theflow of the heating or cooling medium to the SMA portion of actuator arm414 so that it may be uniformly heated or cooled. For example, the hotair flow described above with reference to FIG. 21b, may leave spoke 409through first intermediate port 476 and enter actuator arm 414 throughintake port 490 in the direction of arrow 506, flow through channel 493heating the SMA to above its critical temperature and causing actuatorarm 404 to return to its original shape. The hot air may continue toflow through exhaust port 491 in the direction of arrow 407, exitingactuator arm 414 and reentering spoke 409 through second intermediateport 477.

[0079]FIG. 23 shows an exemplary manner of attaching the actuator armsto the hub and spoke assembly. In this embodiment, first end 430 ofexemplary actuator arm 419 is constructed in a circular shape so thatthe first end 430 fits into circular cavity 510 formed by spokes 404 and409. This construction assures that actuator arms 414-419 are notseparated from hub and spoke assembly 402 in the radial direction asactuator assembly 401 rotates about axis 420 of hub 403, as describedwith reference to FIG. 19. As will be described in greater detail below,actuator assembly 401 may be inserted into a case to prevent actuatorarms 414-419 from separating from hub and spoke assembly 402 in theaxial direction. This construction allows for easy insertion and removalof actuator arms by moving first end 430 in the axial direction into andout of cavity 510. In this embodiment, exhaust port 442 of spoke 404 isadjacent to intake port 460 of actuator arm 419, as described withreference to FIGS. 21a and 22 a, respectively. Similarly, thisembodiment allows first intermediate port 476 of spoke 404 to beadjacent to intake port 490 of actuator arm 419 and second intermediateport 477 of spoke 404 to be adjacent to exhaust port 491 of actuator arm419, as described with reference to FIGS. 21b and 22 b. Those skilled inthe art will understand that there are many possible manners ofconnecting the actuator arms to the hub and spoke assembly, for example,through the use of other integrally formed shapes or by using mechanicalfasteners. In addition, it is possible to form the hub in such a mannerthat the actuator arms may be connected directly to the hub such thatspokes are not necessary.

[0080]FIG. 24 shows an exemplary embodiment of heat converter engine 600powered by an exemplary actuator assembly of the present invention. Heatconverter engine 600 includes actuator assembly 610 which is positionedinside main case 620. First end 631 of drive shaft 630 is insertedthrough opening 611 in actuator assembly 610 and opening 622 in maincase 620. Drive shaft 630 is coupled with shaft 641 of transmission 640through first sealed bearing 650. Second sealed bearing 651 is coupledto second end 632 of drive shaft 630 so that drive shaft 630 may rotatefreely. Insertion of drive shaft 630 through opening 611 in actuatorassembly 610 rigidly couples drive shaft 630 to actuator assembly 610 sothat as actuator assembly 610 rotates inside main case 620, thisrotation is imparted to drive shaft 630. Coupling of drive shaft 630 andactuator assembly 610 may be accomplished by any conventional means. Theaction that drives the rotation of actuator assembly 610 will bedescribed in greater detail below. Actuator assembly 610 is sealedwithin main case 620 by cover 660. As described above, cover 660prevents the actuator arms of actuator assembly 610, for exampleactuator arm 614, from separating from hub and spoke assembly 613 in theaxial direction. A heating medium intake 670 and a cooling medium intake680 are connected to cover 660 which has two vias (not shown) to allowthe heating and cooling mediums to enter the area of main case 620 whenengine 600 is sealed.

[0081]FIG. 25 shows a detail view of exemplary actuator arm 616 ofactuator assembly 610 from FIG. 24. This sectional view shows second end431 of actuator arm 616 that comes in contact with inside cylindricalwall 621 of main case 620 as shown in FIG. 24. Second end 431 ofactuator arm 616 has two sealed bearings 655 and 656. As actuatorassembly 610 rotates within main case 620, sealed bearings 655 and 656come in contact with inside wall 621 and allow actuator assembly 610 torotate freely within main case 620. Those skilled in the art willunderstand that this is only an exemplary embodiment of the portion ofthe actuator assembly that comes in contact with the main case and thatthere are numerous manners of constructing the actuator assembly or themain case such that the actuator assembly will rotate freely while incontact with the inside wall of the main case.

[0082] Referring back to FIG. 24, an exemplary manner of causingactuator assembly 610 to rotate within main case 620 is the following: Acooling medium is input through cooling medium intake 680. The via incover 660 which allows the cooling medium to enter the area of main case620 is positioned so that the cooling medium will enter an intake portof hub and spoke assembly 613 of actuator assembly 610, for example,intake port 441 as described with reference to FIG. 21 a. The coolingmedium will then flow through hub and spoke assembly 613 and intoactuator arms 614-619, cooling actuator arms 614-619 below the criticaltemperature of the SMA, causing actuator arms 614-219 to becomemalleable and able to be deformed from their original shape. As actuatorassembly 610 rotates inside main case 620, only one intake port of aspoke will be positioned adjacent to the via at each instant of time.Thus, cooling medium intake 680, the via and the intake port of thespoke should be sized so that during the single pass in each rotation,enough cooling medium may flow into the actuator arm to cool it belowits critical temperature. However, those skilled in the art willunderstand that it may be possible to design an actuator assembly whereeach actuator arm does not need to be cooled to below its criticaltemperature during each rotation of the actuator assembly.

[0083] In this embodiment, the original shape of actuator arms 614-619is substantially straight as shown in FIG. 24. When the actuator armsare malleable, the force exerted on the arms by coming in contact withinside wall 621 of main case 620 will cause a curvature to be formed inactuator arms 614-619, as described with reference to FIG. 20b. Thoseskilled in the art will understand that, in operation, all of actuatorarms 614-619 of actuator assembly 610 will not simultaneously be intheir original shape as shown in FIG. 24. Some of the arms may be cooledto below the critical temperature of the SMA and have the curved shapedescribed above. In this embodiment, opening 611 of actuator assembly610 will not be centered with respect to main case 620. For example,with reference to FIG. 26, actuator assembly 610 is shown inserted intomain case 620. As shown, actuator arms 617 and 618 are in their originalsubstantially straight shape, actuator arms 616 and 619 have a slightcurvature from the force exerted on these arms from inside wall 621 ofmain case 620, and actuator arms 614 and 615 have the greatestcurvature. Thus, opening 611 in hub and spoke assembly 613 of actuatorassembly 610 is not centered in main case 620 because of the varyingdegrees of curvature on actuator arms 614-619. However, those skilled inthe art will recognize that opening 611, while not centered within maincase 620, will remain at a fixed position while actuator assembly 610rotates. For example, as actuator assembly 610 rotates, actuator arms617 and 618 that are shown in their original substantially straightshape will be cooled to below their critical temperature and the forceexerted by inside wall 621 of main case 620 will cause these actuatorarms to become curved. At the same time, actuator arms 614 and 615 thatare in the fully curved shape will be heated above the criticaltemperature causing these actuator arms to return to their originalsubstantially straight shape. When this occurs the position of actuatorarms 614 and 615 will essentially be interchanged with the position ofactuator arms 617 and 618, respectively. Thus, actuator assembly 610will have rotated one half rotation, but the axis of rotation aboutopening 611 will not change. To account for this offset of the axis ofrotation from the center of main case 620, opening 622 of main case 620may be offset from center to be in line with opening 611 of actuatorassembly 610.

[0084] Again referring back to FIG. 24, when the cooling medium isexhausted from the actuator arm, it flows out of main case 620 throughexhaust port 623. Hub and spoke assembly 613 and actuator arms 614-619maybe similar to those described with reference to FIGS. 21a and 22 a,where the heating or cooling medium is exhausted from the actuatorassembly through an exhaust port on the actuator arm. For example,exhaust port 62 of actuator arm 414 in FIG. 22a. Those skilled in theart will understand that hub and spoke assembly 613 and actuator arms614-619 may also be similar to those described with reference to FIGS.21b and 22 b, where the heating or cooling medium is exhausted from thehub and spoke assembly rather than the actuator arm. For example,exhaust port 472 of the hub and spoke assembly in FIG. 21b. In thiscase, exhaust ports 623 and 624 of main case 620 may be placed in adifferent position to accommodate the exhaust of the heating or coolingmedium.

[0085] Similar to the intake of the cooling medium, a heating medium isinput through heating medium intake 670. The via in cover 660 whichallows the heating medium to enter the area of main case 620 is alsopositioned so that the heating medium will enter an intake port of thehub and spoke assembly 613 of actuator assembly 610, for example, intakeport 441 as described with reference to FIG. 21a. The heating mediumwill then flow through hub and spoke assembly 613 and into actuator arms614-619, heating the actuator arms above the critical temperature of theSMA and causing the actuator arms to resume their original shape. As theactuator arms return to their original substantially straight shape, theforce exerted by the actuator arms in the radial direction againstinside wall 621 of main case 620 will cause the entire actuator assemblyto rotate. Concurrently, the rigidity of the actuator arms that areabove the critical temperature will cause the actuator arms that arebelow the critical temperature to be deformed into the curved shape bybeing forced against inside wall 621 of main case 620. The completeaction of rotation will be described in more detail below. Also, asdescribed above, the heating medium may be exhausted from main case 620through exhaust port 624.

[0086] Referring back to FIG. 26, the rotation of actuator assembly 610within main case 620 will be described in more detail with reference toan exemplary actuator arm. The exemplary actuator arm may be consideredto start at the position of actuator arm 617, where it has beenpreviously heated above the critical temperature of the SMA and is inits original substantially straight shape. As actuator assembly 610rotates in the direction of arrow 625, the intake port of the spoke thatdistributes the heating and cooling medium to the exemplary actuatorarm, for example, intake port 691 of spoke 697 for actuator arm 617,aligns with the via allowing the cooling medium to flow into the spoke.The spoke distributes the cooling medium flow to the exemplary actuatorarm, for example, in the manners described above with reference to FIGS.21a-b and 22 a-b. As described above, the via and intake port should besized so that a sufficient amount of cooling medium flows into the spokewhile the via and intake port are aligned to cool the exemplary actuatorarm below its critical temperature. As actuator assembly 610 continuesto rotate in the direction of arrow 625, the exemplary actuator armrotates into the position of actuator arm 618. In this position, thecooling medium is cooling the actuator arm, but it is not yet below thecritical temperature, therefore, the exemplary actuator arm remains inits substantially straight original shape. When the exemplary actuatorarm is in the position of actuator arms 617 and 618, it is rigid andexerts force in the radial direction against inside wall 621 of maincase 620. Concurrently, this rigidity forces actuator arms oppositethose in the positions of actuator arms 617 and 618, for example,actuator arms 614 and 615 to be deformed into a curved shape to accountfor the rigidity. As actuator assembly 610 continues to rotate in thedirection of arrow 625, the exemplary actuator arm moves into theposition of actuator arm 619. Between the positions of actuator arm 618and 619, the cooling medium has cooled the exemplary actuator arm tobelow the critical temperature so that, when the exemplary actuator armreaches the position of actuator arm 619 it is beginning to be deformedinto the curved shape. Actuator assembly 610 continues to rotate in thedirection of arrow 625 and the exemplary actuator arm rotates into theposition of actuator arm 614, where the force exerted by a rigidactuator arm in the position of actuator arm 617 through hub and spokeassembly 613 causes the exemplary actuator arm to be deformed into thegreatest curvature.

[0087] Continued rotation of actuator assembly 610 in the direction ofarrow 625 causes the intake port of the spoke that distributes theheating and cooling medium to the exemplary actuator arm, for exampleintake port 692 of spoke 694 for actuator arm 614, to align with the viaallowing the heating medium to flow into the spoke and then bedistributed to the exemplary actuator arm. Again, the via and the intakeport should be sized so that a sufficient amount of heating mediumenters the spoke while the intake port and via are aligned to heat theexemplary actuator arm above the critical temperature. As actuatorassembly 610 continues to rotate in the direction of arrow 625, theexemplary actuator arm rotates into the position of actuator arm 615where the heating medium has not yet heated the exemplary actuator armabove the critical temperature. The exemplary actuator arm remains inthe position of greatest curvature because of the force exerted by arigid actuator arm in the position of actuator arm 618. Continuedrotation of actuator assembly 610 causes the exemplary actuator arm tomove between the position of actuator arms 615 and 616, where theheating medium has heated the exemplary actuator arm above the criticaltemperature so that the exemplary actuator arm begins to return to itsoriginal shape. The action of the actuator arm resuming it originalshape causes a force to be exerted in the radial direction againstinside wall 621 of main case 620, which, in turn, causes actuatorassembly 610 to rotate. Finally, as actuator assembly 610 continues torotate, the exemplary actuator arm resumes its original shape when itreaches the position of actuator arm 617.

[0088] Thus, rotation of actuator assembly 610 is accomplished bycontinuous heating and cooling of actuator arms 614-619, where the forceof the actuator arms returning to their original shape causes the entireassembly to rotate. Those skilled in the art will understand that theoriginal and deformed shapes described above, i.e., straight and curved,are only exemplary and that other shapes may also be used for theactuator arms to accomplish the same action of causing the actuatorassembly to rotate. Referring back to FIG. 24, the rotation of actuatorassembly 610 also causes drive shaft 630 to rotate which, in turn,causes shaft 641 of transmission 640 to rotate. Through internal gearingin transmission 640, the rotation of shaft 641 is imparted to rotor 642of transmission 640. The rotation of rotor 642 may be used to drive orpower any number of mechanisms.

[0089]FIG. 27 shows an exemplary embodiment of a system for heating anddelivering a heating medium to the intake of the heat converter engine.FIG. 27 shows exhaust manifold 700 having intake ports 701-704, mainheader 705 and exhaust port 706. Hot exhaust air from the cylinders ofan internal combustion engine enters intake ports 701-704 in thedirection of arrows 711-714, flows through main header 705 in thedirection of arrow 715 and out exhaust port 706 in the direction ofarrow 716. In addition to exhaust manifold 700, this exemplaryembodiment also has medium delivery system 720, having an intake port721, pump 722, heating coil 723 and exhaust port 724. A liquid heatingmedium enters medium delivery system 720 through intake port 721 and ispumped in the direction of arrow 731 by pump 722. The heating mediumentering medium delivery system 720 is cool, or at least not heated toits ideal temperature. As shown in FIG. 27, at point 735, mediumdelivery system 720 enters the boundary of exhaust manifold 700 in thearea of main header 705. In this area, medium delivery system 720 hasheating coil 723. As the heating medium flows through heating coil 723,the flow of hot exhaust air in header 705 heats the heating medium inheating coil 723 to its ideal temperature. Medium delivery system 720then exits the boundary of exhaust manifold 700 at point 736 and theheated heating medium flows in the direction of arrow 734 out exhaustport 724 of medium delivery system 720. The heating medium may then bedelivered to the heating medium intake of the heat converter engine, forexample heating medium intake 670 of FIG. 24.

[0090] Medium delivery system 720 may also be adapted for use by agaseous heating medium by simply using a fan in place of pump 722 tocause gas flow through the system. Alternatively, it may also bepossible to use the hot exhaust flow from exhaust manifold 700 as adirect input to the heating medium intake of the heat converter engine,thereby eliminating medium delivery system 700. Similarly, it may alsobe possible to have a medium delivery system for delivering the coolingmedium to the cooling medium intake of the heat converter engine, forexample cooling medium intake 680 of FIG. 24. For example, the flow ofcooling medium may be cooled by a compressor/condenser unit prior toentering the cooling medium intake. An interesting feature of thecooling medium delivery system may be that the compressor/condenser unitmay be powered by the heat converter engine, after initial start-up,thereby allowing the entire system to be self-contained.

[0091]FIG. 28 shows a first alternative embodiment of an SMA actuatorassembly of the present invention. Actuator assembly 800 has hub andspoke assembly 501 and actuator arms 802-805 and is positioned withinmain case 810. Each of actuator arms 802-805 is constructed of an SMAand has a first end 821 for coupling with hub and spoke assembly 801 anda second end 822 having sealed bearing 823 that comes in contact withthe inside wall 811 of main case 810, allowing actuator assembly 800 tofreely rotate within main case 810. Actuator assembly 800 operates inthe same manner as the previously described actuator assembly in thatthe rotation of actuator assembly 800 within main case 810 is caused bycontinuous heating and cooling of actuator arms 802-805. When actuatorarms 802-805 are cooled they become malleable and are deformed into thecurved shape as shown by actuator arms 802-804, with actuator arm 803having the greatest degree of curvature. As actuator arms 802-805 areheated, they resume their original substantially straight shape, asshown by actuator arm 805. As described above, this action of actuatorarms 802-805 resuming their original shape causes a force to be exertedin the radial direction causing actuator assembly 800 to rotate withinmain case 810.

[0092] In this embodiment, actuator arms 805-805 are heated and cooledby direct application of the heating and cooling mediums to the exteriorof actuator arms 802-805. Main case 810 has a hot gas port 812 and acold gas port 813 which effect the operation of actuator assembly 800 asfollows: An actuator arm in the position of actuator arm 805 has beenheated and is in its original substantially straight shape. As actuatorassembly 800 rotates in the direction of arrow 830, the actuator armcrosses the boundary 814 of cold gas port 813 and an incoming stream ofcold gas flows over the actuator arm cooling it below the criticaltemperature of the SMA. By the time the actuator arm is cooled below thecritical temperature, it has rotated into the position of actuator arm802 and has started to deform into the curved shape. As actuatorassembly 800 continues to rotate in the direction of arrow 830 theactuator arm is further deformed into a more pronounced curvature thatcoincides with boundary 815 of cold gas port 813. Actuator assembly 800continues to rotate in the direction of arrow 830 and the actuator armcrosses boundary 816 of hot gas port 812 into the position as shown byactuator arm 803. In this position, an incoming stream of hot gas flowsover the actuator arm heating it above the critical temperature of theSMA. By the time actuator assembly 800 has rotated in the direction ofarrow 830 so that the actuator arm has reached the position as shown byactuator arm 804, it is heated above the critical temperature and isbeginning to resume its original shape, The actuator arm continues torotate in the direction of arrow 830 until it has fully regained itsoriginal shape as shown by actuator arm 805. This embodiment of theactuator assembly and main case may be used in an heat converter enginesimilar to the one described with reference to FIG. 24.

[0093] FIGS. 29-31 provide a side view of an aircraft landing gear 290,as may be embodied in an alternative embodiment of the presentinvention. In these figures, a Shape Memory Spring (SMS) strut 293, alocking latch 291, a nitrogen filed shock absorber 297, a retractingstrut 295, a tire 296, and a locking spring 294 are shown. FIG. 29illustrates the landing gear 290 in a fully deployed position, FIG. 30shows the landing gear in a semi-retracted position and FIG. 31 showsthe landing gear in a fully retracted position. The aircraft landinggear 290 in this embodiment may be employed in the nose of largeaircraft and as the main landing gear of lighter aircraft. Exemplaryaircraft include airplanes, helicopters, gliders, as well as all othersthat employ retractable landing gear.

[0094] The landing gear 290 may be deployed and locked in an extendedposition during takeoff and landing and may be raised during flight in aretracted, folded, and stowed away position. In this embodiment, thegear may be raised by elongating the SMS strut 293. Then, once thelanding gear 290 is fully retracted, it may be locked in place by thelocking latch 291.

[0095] In this embodiment the SMS strut 293 may contain a shape memoryalloy (SMA) that expands when heated and contracts when cooled. Thisshape memory alloy may be sized to develop the required forces necessaryto raise the landing gear 290. For example, the cross-sectional area maybe sized to be able to develop forces greater than two times thosenecessary to raise the landing gear. This level of force is preferred inthis embodiment in order to provide for a safety factor and also inorder to overcome other dynamic forces encountered shortly after takeoffthat may impede the retraction of the landing gear. Similarly, thelength of the shape memory alloy may also be sized such that thedistance of travel of the landing gear is closely correlated to thedistance of maximum expansion of the shape memory alloy. In other words,when the shape memory alloy within the SMS strut 293 is activated itsmaximum distance of expansion may be 20% greater than the maximumdistance required to fully retract the landing gear 290 into theaircraft's fuselage. By considering the maximum length of the SMA, theforces placed on the landing gear, while the SMS strut is active and thelanding gear 290 is in its retracted position, can be controlled.

[0096] The SMS alloy, resident within the SMS strut 292, may be heatedby various methods including passing an electrical current through it,by positioning it near a heat generating resistor or by passingthermally charged fluids over and around it. These sources of heat maycommunicate with the SMS strut via a shape memory spring strutactivation line (not shown). In each case and in the various otherplausible methods of heating the shape memory alloy, as the shape memoryalloy is heated it will expand and, acting through the various membersand linkages of the landing gear, cause the landing gear to retract.Once locked in the retracted position, via a locking hatch or otherapparatus, the shape memory alloy may be allowed to cool. Once cooled,the SMA will no longer place a lifting force on the landing gear. Thus,in the retracted state the landing gear is maintained in a foldedposition via the locking latch 291. When required, the landing gear 290may be lowered by unlocking the locking latch 291 and allowinggravitational and locking spring 294 forces to lower it. The lockinglatch 291 may be unlocked by pulling on chord 292 although numerousother embodiments are also plausible for releasing the landing gearincluding the use of additional SMAs, SMSs, locking solenoids or otherlocking mechanisms. Once released and free to move, forces generated byspring 294 may supplement the gravitational forces that will urge thelanding gear 290 back into its fully deployed and locked position.

[0097]FIG. 32 is a side view of the landing gear employing an SMS strutactivated by an internal shape memory alloy as installed in a noselanding gear of a light passenger airplane. FIG. 32 contains the nose320 of a light passenger airplane, an SMS strut 325, a nitrogen filledshock absorber 322, a retracting strut 324, and a locking spring 323. Italso illustrates a line of travel of the landing gear with dashed line321. As can be seen in FIG. 32 the line of travel 321 creates an arclike curve in this embodiment.

[0098] In addition to the embodiments described above, numerous otherembodiments are also plausible to facilitate the raising and lowering ofaircraft landing gear. For example, the struts and springs may bereconfigured such that the contraction of SMS strut generates therequired forces to raise the landing gear. Furthermore, rather thanusing electrical currents to facilitate the expansion of the strutsother sources of thermal energy may be employed. For example heated airmay be forced across the shape memory alloy in the strut to cause it toexpand in a different embodiment, likewise other fluids, such as wateror oil may be used to heat the shape memory alloy. Moreover, in theseembodiments, a shape memory spring strut activation line (not shown) mayin fluid communication with a pump that urges these compressible andnon-compressible fluids towards the SMA. Once the fluids reach the SMAit will expand in reaction to the thermal energy transferred by thefluid.

[0099] FIGS. 33-36 show a landing gear as may be employed in a largeraircraft. FIG. 33 shows the landing gear 330 in a fully deployedposition under static load; FIG. 34 shows the landing gear 330 in afully deployed position when the aircraft is airborne; FIG. 35 shows thelanding gear 330 in a partially retracted position; and, FIG. 36 showsthe landing gear 330 in a fully retracted position. As described above,the landing gear contains an SMS strut 331 that generates the liftingforce to lift the undercarriage via the expansion of the shape memoryalloy resident within it. Like the embodiment described above, the shapememory alloy may be activated through various heat introductionmethodologies including electrical current and thermal transfer fluids.In this embodiment, rather than having a locking mechanism hold the gearin a retracted position the SMS strut is activated throughout the entireflight time to keep the landing gear retracted. Then, when necessary,the shape memory alloy is allowed to cool and, thus, allow the landinggear to retract back down into a locked position.

[0100]FIG. 37 is a profile view of a windshield wiper arm as may beemployed by a motor vehicle such as a motorcycle, a motor boat, and anautomobile in accord with an alternative embodiment of the presentinvention. During high speeds the airflow over the windshield of a motorvehicle (not shown) may lift the wiper blade 370 off of the glass andthereby reduce the wiper blade's 370 effectiveness. In order to overcomethese high speed lifting forces, a downward force, opposing the liftingforce, may be generated to hold the wiper blade 370 against the glass.

[0101]FIG. 38 is an enlarged view of the circled area in FIG. 37. InFIG. 38 the SMS coil 383 is shown in an energized state. Clearly evidentin FIG. 38 are the wiper arm head 388, pivot pin 385, wiper blade pin386, wiper arm 381, wiper blade connection 387, reaction arrow 380,rotation arrows 3800, force arrow 384, power supply line 382, SMS coil383, and chassis 389.

[0102]FIG. 39 also provides an enlarged view of the circled area in FIG.37. In FIG. 39 the SMS coil 383 is shown in a relaxed state. In FIG. 39,as the SMS coil 383 is shown in a relaxed state, the reaction arrow 391,rotation arrows 390, and force arrow 392 are opposite those in FIG. 38.

[0103] In use, in order to create an additional inward force by thewiper arm 381 against the windscreen once the motor vehicle has reacheda minimum target speed, an electrical voltage may be applied to heatingelement 3810 in order to heat SMS coil 383. Upon being heated, the SMScoil 383, which contains an SMA, will expand and begin to place a forceon the rocker arm 3820. The direction of this force is illustrated byarrow 384. This force causes the rocker arm 3820 to rotate as shown byrotation arrows 3800. As the rocker arm 3820 rotates a reaction forceillustrated by reaction arrow 380 is generated. This reaction forceurges the wiper blades into the windscreen and thus creates a greatercontact force between the wiper blades (not shown) and the windscreen(not shown). Then, as the vehicle slows or the additional forces are nolonger needed, the voltage will be removed and the SMS coil 383 may beallowed to relax back to its original length. No longer exerting a forceagainst the rocker arm 3820, the arm will rotate back to its relaxedposition under biasing forces generated by springs which are not shown.

[0104] Rather than using a heating coil 3810 to generate the thermalenergy that will facilitate the expansion of the SMS coil 383, othermethods of heating the SMS coil may also be employed. These methodsinclude placing a voltage source directly in contact with the SMS coil383 and allowing its internal electrical resistance to generate the heatneeded to enlarge the coil or forcing thermal conduction fluid over andin contact with the SMS coil to provide the requisite thermal energy.The thermal conduction fluid may be engine oil pumped from the crankcase and regulated by a valve controlled by a processor in the motorvehicle.

[0105]FIG. 40 provides an alternative embodiment wherein rather thanpushing up on a rocker arm as described above, an SMS coil is placedwithin the wiper arm head to facilitate the urging of the wiper bladesagainst the glass. In this embodiment, when additional inward force isrequired to keep the wiper blade against the glass, the SMS coil 403 maybe heated via an electrical line, thereby causing it to shrink andcreate an additional inward force. to FIGS. 41-42 provide a side view ofan automobile power door lock assembly 413 in accord with anotheralternative embodiment of the present invention. These door lockingassemblies 413 contain a locking head 411, an SMS coil 412, and abushing 415. The SMS coil 412 may be used to slide the locking head 411back and forth as indicated by arrows 414. The SMS coil 412 may beactivated by applying a voltage to it or otherwise heating it. Uponbeing heated the SMS coil 412 may expand and urge the locking head 411into one position. Once the heat is removed from the SMS coil 412 abiasing force generated by the bushing 415 may urge the locking head 411back to its original position. Alternatively, in another embodiment, twoSMS coils may be used to move the locking head back and forth. In thisalternative embodiment an ongoing current need not be sustained tomaintain the SMS coil in an extended position to resist the biasingforce of the bushing.

[0106] FIGS. 43 provides a moveable solar array in accord with anotheralternative embodiment of the present invention. In this embodiment asolar array 431 is pivotably mounted on a frame 433 and is moveable viaSMS coils 432. These SMS coils are in optical communication withfocusing lenses 435. These focusing lenses may be positioned as to focusthe ambient rays of the sun onto the SMS coils 432. These focusinglenses 435 and SMS coils 432 work in unison with each other to rotatethe face of the solar array in conjunction with the movement of the Suncaused by the Earth's rotation. As the Sun moves across the sky its rayswill non-uniformly heat the various SMS coils 432 supporting the solararray. Thus, the SMS coils that receive more of the Sun's rays will beheated to a greater degree and will shrink, thereby pulling the face ofthe solar array towards the Sun. Then, as the Sun moves across the sky,its rays will reach the SMS coils 432 in increasing and decreasingintensities causing the face of the array to rotate and track it acrossthe sky. In short, when one SMS coil 432 receives more light itsdownward forces will increase while another SMS coil 432 will receiveless light, thereby reducing its downward pulling forces.

[0107] The focusing lenses 435 may be used to increase the intensity ofthe radiant energy reaching the coils. Alternatively, when the amount oflight reaching the solar array is large enough, as may be the case inceratin equatorial regions or in outer space, the focusing lenses maynot be needed.

[0108]FIG. 44 provides an alternative embodiment wherein the focusinglenses 435 have not been employed as may be used in a self-adjustingsatellite solar array.

What is claimed is:
 1. A retractable aircraft landing gear systemcomprising: a shape memory spring strut having a first end and a secondend, the shape memory spring strut extendable from a first length to asecond length, the shape memory spring strut containing a shape memoryalloy; a shape memory spring strut activation line connected to theshape memory spring strut, the shape memory spring strut activation lineconfigured to activate the shape memory spring strut; and a longitudinalconnecting member having a first segment and a second segment, the firstsegment in pivotal contact with the first end of the shape memory springstrut and the second segment supporting a wheel rotatably mounted on apin, the connecting member moveable along a line of travel from anextended position to a retracted position.
 2. The retractable aircraftlanding gear system of claim 1 further comprising: a locking latchpositioned to contact and hold the longitudinal connecting member in theretracted position.
 3. The retractable aircraft landing gear system ofclaim 2 further comprising: a cable connected to the latch, the cableslidable from a first position to a second position.
 4. The retractableaircraft landing gear system of claim 1 wherein the shape memory springstrut activation line is an electrical line.
 5. The retractable aircraftlanding gear system of claim 4 further comprising: an electricalresistor in electrical communication with the shape memory spring strutactivation line.
 6. The retractable aircraft landing gear system ofclaim 1 wherein the shape memory spring strut activation line is a fluidconduit.
 7. The retractable aircraft landing gear system of claim 6further comprising: a fluid pump connected to the fluid conduit, thepump adapted to force heated fluid through the fluid conduit to theshape memory spring strut.
 8. The retractable aircraft landing gearsystem of claim 7 wherein the fluid is engine oil.
 9. A method ofretracting aircraft landing gear comprising: activating a shape memoryalloy within a shape memory spring strut, the shape memory alloy beingactivated via a shape memory spring strut activation line in contactwith the shape memory spring strut, the shape memory spring strut havinga first end and a second end and being extendable from a first length toa second length, the first end of the shape memory spring strut inpivotal contact with a first segment of a longitudinal connecting memberalso having a second segment, the second segment supporting a wheelrotatably mounted on a pin, the longitudinal connecting member moveablealong a line of travel from an extended position to a retractedposition.
 10. The method of claim 9 further comprising: locking thelongitudinal connecting member in a fixed position.
 11. The method ofclaim 9 wherein the shape memory alloy is activated by raising itstemperature with thermal energy carried by a fluid.
 12. The method ofclaim 9 wherein the shape memory alloy is activated by raising itstemperature with thermal energy created through resistance to electricalcurrent flow.
 13. The method of claim 9 further comprising: locking thelongitudinal connecting member in a fixed position; and de-activatingthe shape memory alloy within the shape memory strut.
 14. The method ofclaim 13 further comprising: unlocking the longitudinal connectingmember by opening a locking latch.
 15. The method of claim 11 whereinthe fluid is engine oil.